Six million gallons of oil have been dumped into the Gulf of Mexico since a Louisiana rig exploded and sank there on April 20.

Louisiana oil spill

Crude oil has been pouring out the busted well for more than 40 days at a rate of 19,000 barrels (800,000 gallons) a day since an explosion April 20 that demolished the company's Deepwater Horizon oil rig killing 11 crewmen and unleashing the worst ever oil spill in US history.